Texture and Optical Studies of the Mesophases of Cyanocyclohexyl Cyclohexanes

Optical studies have been conducted as a function of temperature on two (CCH₃ and CCH₇) of the three odd members of the homologous series of the mesogen trans, trans-4′-alkyl-bicyclohexyl-4-carbonitrite. From birefringence studies the variation of the orientational order parameter ? P₂ ? with temperature of the two members has been determined. Texture studies have been conducted to identify hitherto unidentified phases. A comparative study of the temperature dependence of the refractive indices n _e, n _o , and ? P₂ ? of all the three members CCH₃, CCH₅, CCH₇ have been presented with a view to study the effect of increasing chain length. Comparison of the experimentally obtained ? P₂ ? values has been made with theoretical values predicted by the Maier-Saupe theory.